CN107000816A - The method and system of the goods fluid of sea transfer outside - Google Patents

Abstract

The method and system of goods fluid is shifted between the first ship (1) and the second ship (10) of marine configured in parallel outside, wherein the first ship (1) is equipped with goods tie point (6), and wherein the second ship (10) is equipped with cargo manifold (14), and wherein tubulose pipeline (20) can be connected between goods tie point (6) and cargo manifold (14), wherein this method includes：Self-propelled buoy (12) is attached to the second ship (10)；Goods connector (16) is connected between self-propelled buoy (12) and cargo manifold (14)；Goods pipeline (18) is connected between goods tie point (6) and self-propelled buoy (12)；Goods is shifted between goods tie point (6) and cargo vessel (10)；When self-propelled buoy (12) is attached to the second ship (10), self-propelled buoy (12) is maintained in the preset distance border (36,38) relative to the first ship (1) by self-propelled buoy (12).

Description

Method and system for transferring cargo fluids at sea

technical field

A method for transferring cargo fluid (fluid bulk cargo) on open sea (open sea) is provided. More precisely, there is provided a method for transferring cargo fluids on open seas between a first vessel and a second vessel in a parallel configuration (parallel configuration), wherein the first vessel is equipped with a cargo connection point , and wherein the second vessel is equipped with a cargo manifold, and wherein a tubular line can be connected between the cargo connection point and the cargo manifold. The invention also includes a system for transferring cargo fluids on open seas.

Background technique

For illustration purposes, hereinafter, the first vessel is referred to as a floating LNG production storage and offloading vessel (FLNG), while the second vessel is referred to as a Liquefied Natural Gas Carrier (LNGC). This example is purely illustrative and does not limit the scope of the invention in any way.

The term "fluid" includes both liquid and gaseous products.

Two methods and systems for transferring fluids between ships on open seas are commonly used: the so-called "tandem system" and the "side-by-side system".

When the tandem system (Tandem System) is used, the LNGC is usually located at a position of 80m-150m from the stern of the FLNG ship and is under "down weather". Since the ships are kept at a distance from each other, this method is relatively safe from a collision point of view. Therefore, loading operations can be carried out under relatively large wave conditions.

Since LNGCs themselves typically have a manifolded mid-hull section, the cargo hoses (which may be suspended in the air, floating on the surface or even submerged) tend to be relatively long. Longer hoses generally create a greater pressure drop than shorter hoses and often require a booster pump to overcome the pressure drop. When loading LNG, longer hoses produce more boil-off gas and may require a relatively large boil-off handling system.

When using a side-by-side system, the LNGC is moored side-by-side relative to the FLNG. The distance between the two is only a few meters. Side-by-side systems are relatively sensitive to weather conditions due to the risk of collision between ships.

The main advantage of the side-by-side system is the relatively short distance between the manifold of the LNGC and the FLNG. A conventional loading arm, short hose or similar extending through the gap between the two vessels may be used. There is therefore no need for floating hoses or underwater hoses exposed to waves and currents. Due to the short length of the fluid transfer system, the pressure drop in the hose is low and standard pumps can be used. The amount of boil-off gas is also significantly reduced when LNG is loaded.

Patent document EP 2121462 shows a vessel fitted with azimuth thrusters to improve maneuverability during loading operations.

In this document, the term "parallel" configuration is used primarily to distinguish the method and system of the present invention from a "side-by-side" configuration. The meaning of the term "parallel" configuration is defined in the description below and includes positioning of a second vessel by means of a self-propelled buoy (buoy) relatively close to the first vessel.

Contents of the invention

It is an object of the present invention to overcome or alleviate at least one disadvantage of the prior art, or at least to provide an advantageous alternative with respect to the prior art.

This object is achieved by the features described in the following description and appended claims.

A method for transferring cargo fluid between ships on open seas is provided. A cargo line can be connected between the first vessel and the self-propelled buoy. The self-propelled buoy is attachable to a second vessel and the self-propelled buoy is designed to safely maintain the self-propelled buoy at a predetermined distance boundary relative to the first vessel when the second vessel is attached to the self-propelled buoy in a parallel configuration Inside.

The self-propelled buoy is equipped with a cargo connection that can be connected to a manifold on a second vessel.

The invention is defined by the independent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect, the present invention relates more particularly to a method for transferring cargo fluids between a first vessel and a second vessel in a parallel configuration on the open sea, wherein the first vessel is equipped with a cargo connection point, and Wherein the second vessel is equipped with a cargo manifold, and wherein a tubular line is connectable between the cargo connection point and the cargo manifold, wherein the method comprises:

- attaching the self-propelled buoy to the second vessel;

- connection of the cargo connection between the self-propelled buoy and the cargo manifold;

- connection of the cargo line between the cargo connection point and the self-propelled buoy;

- transfer of cargo between the cargo connection point and the second vessel; and

- When attaching the self-propelled buoy to the second vessel, by means of the self-propelled buoy to keep the self-propelled buoy within a predetermined distance boundary relative to the first vessel.

The method may include allowing the second vessel to turn by a predetermined angle relative to the first vessel.

The method may include attaching the self-propelled buoy to the second vessel prior to connecting the cargo line between the cargo connection point and the self-propelled buoy.

In general terms, the first vessel may be designed as (a type of) vane around a moored swivel. Thus, the first vessel may turn according to the direction of a resultant unit force (which may include force components from wind and current). The composite unit forces may include any of wind, wave, and water current forces.

However, the first vessel may be equipped with thrusters designed to keep the heading fixed during parallel loading operations even when the resultant unit force slightly changes its direction.

If the resultant unit force changes and the first vessel maintains its heading, it may be desirable to rotate the second vessel relative to the first vessel in order to resist the resultant unit force.

Even though a standard secondary vessel may not have propellers or bow thrusters, all suitable secondary vessels have propulsion machinery including rudders and auto-pilots. In one embodiment of the method, after connecting the self-propelled buoy to the second vessel, the desired orientation of the second vessel may be maintained by the propulsion machinery controlled by the second vessel's autopilot.

The self-propelled buoy can position and maintain the second vessel in a desired position relative to the first vessel, while the desired course of the second vessel can be maintained by the second vessel itself.

For safety reasons, it may be the best procedure to attach the self-propelled buoy to the second vessel at some distance (eg two or three nautical miles) from the first vessel. Subsequently, the self-propelled buoy can safely bring the second ship to a safe distance, for example between 50 meters and two to three hundred meters from the first ship. A distance of about one hundred meters may be considered ideal from a safety and cargo line length point of view.

The method may include emergency disconnection of the cargo line between the cargo connection point and the self-propelled buoy, and gradually drifting the second vessel to which the self-propelled buoy is attached away from the first vessel.

The cargo line can be disconnected if an unsafe situation would occur. Since there is then no mooring connection between the vessels, the second vessel can gradually drift away from the first vessel, or be moved away from the first vessel by an attached self-propelled buoy.

The method can include:

- first, attaching a DPS self-propelled buoy to a second vessel; and

- Subsequently, attaching the self-propelled buoy with the cargo line connected to it to the second vessel.

The term DPS (Dynamic Positioning System) is used here to distinguish between the two self-propelled buoys. Both may or may not have DPS.

In some cases it may be desirable to attach a DPS self-propelled buoy at a distance from the first vessel and have the DPS self-propelled buoy bring the second vessel to a safe distance relative to the first vessel. The self-propelled buoy may then have been connected to the cargo line before attaching itself to the second vessel. Thus, the total time for attaching, connecting and loading can be significantly reduced since the task of picking up the second vessel can be taken up by the DPS self-propelled buoy and the cargo line can be cooled before attaching the self-propelled buoy.

Another advantage of having one self-propelled buoy on each side of the second vessel may be a particularly pronounced damping effect on the rolling motion of the second vessel. This may be especially important when loading or unloading so-called membrane LNG carriers, which are often sensitive to sloshing of the LNG.

In a second aspect, the invention relates more particularly to a system for transferring cargo fluids between a first vessel and a second vessel in a parallel configuration on open sea, wherein the first vessel is equipped with a cargo connection point, and wherein The second vessel is equipped with a cargo manifold, and wherein a tubular line can be connected between the cargo connection point and the cargo manifold, wherein at least one self-propelled buoy can be connected to the second vessel, said self-propelled buoy being designed to Connected to the cargo line extending from the cargo connection point, a cargo connection is connectable between the self-propelled buoy and the cargo manifold of the second vessel, and wherein the self-propelled buoy is designed such that when the self-propelled buoy is attached to the second vessel When two vessels are present, the self-propelled buoy is maintained within a predetermined distance boundary relative to the first vessel.

This first vessel can be designed as a vane (pattern), thereby adapting itself to the resultant unit force direction.

The cargo connection point may be located remotely from the flare tower on the first vessel. A preferred location for the cargo connection point may be at the stern part of the first vessel, as this part of the first vessel may generally be relatively less equipped with other equipment.

Furthermore, if (or when) the cargo connection point is located on the stern portion of the first vessel, the second vessel is further away from the first vessel than if the cargo connection point were positioned further forward on the first vessel. And the distance that may have to be moved can be shorter.

The first vessel may be equipped with a support boom or drum for the cargo line. Thereby, the cargo line can be kept out of the sea water.

For some cargoes, the cargo line may be in the form of a rigid pipe with a swivel to avoid (use) flexible lines.

The cargo line between the cargo connection point and the self-propelled buoy may take the form of a submersible or floatable hose or flexible line, if preferred.

A service vessel is connectable to the second vessel, in particular to the bow of the second vessel, for example to assist the self-propelled buoy in keeping the course of the second vessel in line with the first vessel.

The aforementioned predetermined distance boundary may be defined by an inner distance boundary and an outer boundary, the inner distance boundary may be defined for safety reasons, and the outer boundary may be defined by the length of the cargo pipeline.

Methods and systems according to the present invention may have the benefit of combining the advantages of side-by-side and tandem loading systems. For example, the relatively short flow line from the first vessel to the cargo manifold typical of side-by-side systems can be maintained, while also benefiting from the improved safety factor typical of tandem systems.

Description of drawings

Examples of preferred embodiments of the invention are described below as illustrated in the accompanying drawings, in which:

Figure 1 shows a plan view of a first vessel and a second vessel connected for transferring cargo fluids according to the present invention;

Figure 2 shows, on a larger scale, an end view of the self-propelled buoy during attachment of itself to a second vessel;

Figure 3 shows an end view of the situation in Figure 1 on a larger scale;

Figure 4 shows a plan view of a situation in which the second vessel is allowed to gradually drift away from the first vessel;

Figure 5 shows a plan view of a first vessel and a second vessel in an alternative embodiment; and

Figure 6 shows a plan view of a first vessel and a second vessel in another alternative embodiment.

detailed description

In the figures, reference numeral 1 denotes a first vessel connected to a mooring swivel 2 and equipped with a flare tower 4 and a cargo connection point (location) 6 . In Figures 1 and 4, the cargo connection point 6 is provided at the stern part 8 of the first vessel 1, whereas in Figure 6 the cargo connection point is provided at the intermediate vessel. The first vessel 1 may have more than one cargo connection point 6 in order to be able to load more than one second vessel 10 at the same time.

The second vessel 10 has a self-propelled buoy 12 attached near its cargo manifold 14 . Cargo connection 16 connects self-propelled buoy 12 to cargo manifold 14 .

A cargo line 18 connects the cargo connection point 6 to the self-propelled buoy 12 . In this embodiment, tubular line 20 includes cargo connection 16 and cargo line 18 providing a flow path for cargo fluid between cargo connection point 6 and cargo manifold 14 .

As shown in FIG. 3 , cargo line 18 is at least partially carried by boom 22 . In some cases, the cargo line 18 may include a hard pipe 24 with a swivel 26 , or a buoyant or submerged hose 28 as shown in phantom in FIG. 3 .

The service vessel 30 is optionally attached to the bow 32 of the second vessel 10 by means of bridle lines 34 .

When cargo is to be transferred (delivered) between the first vessel 1 and the second vessel 10 , the self-propelled buoy 12 touches the second vessel 10 at a distance from the first vessel 1 . After the self-propelled buoy 12 is attached to the second vessel 10, the self-propelled buoy 12 brings the second vessel 10 towards the first vessel 1, wherein the self-propelled buoy 12 will stay at a predetermined distance boundary 36, 38 from the first vessel 1 Inside. Once attached, the service vessel 30 assists in maintaining the second vessel 10 in a desired orientation relative to the first vessel 1 .

The cargo connection 16 and cargo line 18 are connected and after normal preparations the cargo fluid transfer is initiated. When complete, the reverse program is started.

When transferring cargo such as LNG (Liquefied Natural Gas), at least one cargo line 18 for liquid transfer and return cargo line 18 for return of vaporized gas is generally used.

If the resultant unit force is changed, the second vessel may be allowed to turn an angle 40 relative to the first vessel 1 , as shown in FIG. 1 .

In an emergency situation, the cargo line 18 can be separated from the self-propelled buoy 12, after which the second vessel 10 can gradually drift away from or move away from the first vessel 1, usually via the self-propelled buoy 12, as shown in FIG.

In an alternative embodiment shown in FIG. 5 , a self-propelled buoy 12 holds the second vessel 10 in a desired position relative to the first vessel 1, while at the same time the propulsion machinery 42 (preferably automatically) maintain the heading (heading) of the second vessel 10 .

A number of available collision avoidance systems between the first vessel 1 and the second vessel 10 are outlined in FIG. 5 .

Firstly, due to the resultant unit force 46, the first vessel 1 will become a weather vane. Thus, the second vessel 10 may be positioned at the stern of the first vessel 1 and the resultant unit force 46 will tend to move the second vessel 10 away from the first vessel 1 . Furthermore, in most cases the first vessel 1 has a propeller 48 which can be used to turn the first vessel 1 away from the second vessel 10 . The self-propelled buoy 12 can then push the second vessel 10 away from the first vessel 1 and eventually the propulsion machinery 42 of the second vessel 10 can move the second vessel away.

Even in the event of a complete blackout (blackout) of one or both of these systems, the remaining functional systems are sufficient to avoid a collision. And, in the most unlikely case where all active propulsion systems stop simultaneously, the resultant unit force 46 will push the second vessel 10 safely away from the first vessel 1 .

In another alternative embodiment shown in FIG. 6 , a DPS self-propelled buoy 50 is first attached to the second vessel 10 . When the DPS self-propelled buoy 50 has brought the second vessel 10 to the first vessel 1 , the self-propelled buoy 12 with connected and cooled cargo line 18 is attached to the second vessel 1 . This method significantly reduces the preparation time for transferring the cargo fluid.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "to comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements.

The mere fact that certain features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be used to advantage.

Claims (14)

1. A method for transferring cargo fluids on open seas between a first vessel (1) and a second vessel (10) arranged in parallel, wherein said first vessel (1) is equipped with a cargo connection point (6 ), and wherein said second vessel (10) is equipped with a cargo manifold (14), and wherein a tubular line (20) is connectable between said cargo connection point (6) and said cargo manifold (14) , characterized in that the method includes: - attaching a self-propelled buoy (12) to said second vessel (10); - connecting a cargo connection (16) between said self-propelled buoy (12) and said cargo manifold (14); - connecting a cargo line (18) between said cargo connection point (6) and said self-propelled buoy (12); - transferring cargo between said cargo connection point (6) and said second vessel (10); - when attaching said self-propelled buoy (12) to said second vessel (10), by means of said self-propelled buoy (12) to maintain said self-propelled buoy (12) relative to said second vessel Within a predetermined distance boundary (36, 38) of a vessel (1). 2. A method according to claim 1, wherein the method comprises allowing the second vessel (10) to turn by a predetermined angle (40) relative to the first vessel (1). 3. A method according to claim 1 or 2, wherein the method comprises, prior to connecting the cargo line (18) between the cargo connection point (6) and the self-propelled buoy (12), The self-propelled buoy (12) is attached to the second vessel (10). 4. A method according to any one of the preceding claims, wherein the method includes allowing the second vessel (10) to (42) to maintain the desired course of the second vessel. 5. The method according to any one of the preceding claims, wherein the method comprises emergency disconnection of the cargo line ( 18), and gradually drift away from the first ship (1) with the second ship (10) attached with the self-propelled buoy (12). 6. The method according to any one of the preceding claims, wherein the method comprises: - first, attaching a DPS self-propelled buoy (50) to said second vessel (10); - Subsequently, attaching said self-propelled buoy (12) with said cargo line (18) connected to said second vessel (10). 7. A system for transferring cargo fluids on open seas between a first vessel (1) and a second vessel (10) arranged in parallel, wherein said first vessel (1) is equipped with a cargo connection point (6 ), and wherein said second vessel (10) is equipped with a cargo manifold (14), and wherein a tubular line (20) is connectable between said cargo connection point (6) and said cargo manifold (14) , characterized in that at least one self-propelled buoy (12) is connectable to said second vessel (10), said at least one self-propelled buoy being designed to be connectable to cargo extending from said cargo connection point (6) a pipeline (18) having a cargo connection (16) connectable between said self-propelled buoy (12) and the cargo manifold (14) of said second vessel (10), and wherein said self-propelled buoy ( 12) is designed to maintain said self-propelled buoy (12) in relation to said first vessel (1) when said self-propelled buoy (12) is attached to said second vessel (10) within a predetermined distance boundary (36, 38). 8. The system according to claim 7, wherein the first vessel (1) is designed as a weathervane. 9. A system according to claim 7 or 8, wherein the cargo connection point (6) is located remotely from the flare tower (4) on the first vessel (1). 10. A system according to any one of claims 7 to 9, wherein the cargo connection point (6) is in the stern part of the first vessel (8). 11. The system according to any one of claims 7 to 10, wherein the first vessel (1) is equipped with a support derrick (22) for the cargo line (18). 12. The system according to any one of claims 7 to 11, wherein the cargo line (18) is a hard pipe (24) with a swivel (26). 13. A system according to any one of claims 7 to 12, wherein the cargo line (18) takes the form of a submersible or buoyant hose. 14. The system according to any one of claims 7 to 13, wherein a service vessel (30) is connectable to the second vessel (10).